Hitherto, in various display apparatuses such as a liquid crystal display, a plasma display, and a CRT display, if external light of a fluorescent lamp or the like is reflected onto the surface, visibility is remarkably deteriorated. Therefore, there is used a method whereby a reflectance is decreased by forming an optical multilayer film or a film of a low refractive index onto the surface of the display apparatus or the external light is diffused and reflected by forming an anti-glare film having micro concave/convex portions on the surface, thereby blurring a reflected image.
However, there is such a problem that if the optical multilayer film is used, manufacturing costs increase, an anti-glare property is insufficient, and even if the manufacturing costs are suppressed by using the low refractive index film, the reflectance is relatively high, so that the user is conscious of the reflected image.
On the other hand, the method whereby the anti-glare film having the micro concave/convex portions on the surface is used and the reflected image is blurred by the diffuse reflection is widely used because it is reasonable and high productivity is obtained.
A construction of a conventional anti-glare film 101 is shown in FIG. 10. The anti-glare film 101 has: a substrate 111; and an anti-glare layer 112 formed on the substrate 111. The anti-glare layer 112 is formed by a resin containing fine particles 113 made of irregular silica or resin beads. By projecting the fine particles 113 from the surface of the anti-glare layer 112, micro concave/convex shapes are formed on the surface. The anti-glare film 101 is formed by coating the substrate 111 with a coating material containing the fine particles 113, a resin, a solvent, and the like and drying the coating material. According to the anti-glare film 101 having the construction mentioned above, since light which enters the anti-glare layer 112 is scattered by the fine particles 113 projected from the anti-glare layer 112, a reflected image due to the surface reflection is blurred.
According to the anti-glare film 101, however, although the anti-glare property is obtained, since the concave/convex portions are formed on the surface by the projecting shape of each fine particle 113, there is such a problem that a haze value rises due to the projections of those fine particles 113, an image becomes whitish, and particularly, in the case where the external light is strong, a contrast decreases, visibility deteriorates, and image visibility also deteriorates.
Therefore, as shown in FIG. 11, such a technique that a filling rate of the fine particles 113 in the anti-glare layer 112 is reduced and a cycle of the concave/convex portions on the surface of the anti-glare layer 112 is extended, thereby raising the contrast has been proposed. However, if it is intended to realize the smooth concave/convex shapes by extending the cycle or the concave/convex portions on the surface of the anti-glare layer 112 as mentioned above, flat portions are formed between the projections of the fine particles 113, so that the anti-glare property deteriorates.
Therefore, in recent years, a surface treatment in which an appearance of white muddiness is suppressed and the contrast is high while the anti-glare property is held has been demanded and various methods of realizing such a surface treatment have been being examined. For example, an anti-glare film in which by controlling a mean diameter of fine particles, an average slope angle which is formed by the fine particles, and display contrast characteristics, a deterioration in contrast is suppressed while maintaining an anti-glare property has been disclosed in JP-A-2007-41533.
However, since there is a contradictory relation between both characteristics of the anti-glare property and the contrast, it is difficult to design an anti-glare film which can satisfy them and it is demanded to further improve both of those characteristics. For example, as disclosed in JP-A-2007-415533 mentioned above, it has been known that when the mean diameter of the fine particles, the average slope angle, and the display contrast characteristics are merely controlled, it is difficult to obtain the sufficient anti-glare property and contrast.